1. Field of the Invention
The present invention relates generally to electrical circuits, and more particularly but not exclusively to time-to-digital converters.
2. Description of the Background Art
Time-to-digital converters are widely used to measure the timing difference between two signals. As an example, a time-to-digital converter may receive a first signal, thereafter receive a second signal, and then output a digital signal indicative of the timing difference between the first and second signals. Characteristics of a time-to-digital converter include detection range, timing resolution, and non-linearity. Detection range is the largest timing difference that the time-to-digital converter can measure. A circular time-to-digital converter takes advantage of its re-circular nature to reduce the number of delay cells employed while increasing detection range. However, the minimum timing difference, i.e. timing resolution, which can be detected by the circular time-to-digital converter is still subject to the delay of each of its delay cells. Embodiments of the present invention pertain to a circular time-to-digital converter with improved timing resolution.